The present invention relates to the fabrication of magnetic devices. More particularly, the present invention relates to controlling the rate of modification of a write element tip using a galvanic couple.
In a magnetic data storage and retrieval system, a thin-film transducing head typically includes a transducer, a substrate upon which the transducer is built, and an overcoat deposited over the transducer. The transducer, which is formed of multiple patterned layers successively stacked on the substrate, typically includes a writer portion for recording and storing magnetically-encoded information on a magnetic medium and a reader portion for retrieving the magnetically-encoded information from the magnetic medium. The volume of the transducer is typically much smaller than the volume of the substrate.
The layers of the transducer, which include both metallic and insulating layers, have differing mechanical and chemical properties than the overcoat. These differences in properties may cause the layers of the transducing head to be lapped or polished at different rates. Thus, when the medium confronting surface of the transducing head is lapped during its fabrication, differing amounts of the layers may be removed, resulting in an uneven medium confronting surface. For example, a greater amount of the metallic layers of the transducer may be removed during the lapping process than of the substrate material. This may result in pole tip recession (PTR), in which the medium confronting surface of the write element or pole is recessed from the medium confronting surface of the substrate.